var ZEROES = Buffer.alloc(16, 0);
function toArray(buf) {
    return [
        buf.readUInt32BE(0),
        buf.readUInt32BE(4),
        buf.readUInt32BE(8),
        buf.readUInt32BE(12)
    ];
}
function fromArray(out) {
    var buf = Buffer.allocUnsafe(16);
    buf.writeUInt32BE(out[0] >>> 0, 0);
    buf.writeUInt32BE(out[1] >>> 0, 4);
    buf.writeUInt32BE(out[2] >>> 0, 8);
    buf.writeUInt32BE(out[3] >>> 0, 12);
    return buf;
}
function GHASH(key) {
    this.h = key;
    this.state = Buffer.alloc(16, 0);
    this.cache = Buffer.allocUnsafe(0);
}
// from http://bitwiseshiftleft.github.io/sjcl/doc/symbols/src/core_gcm.js.html
// by Juho Vähä-Herttua
GHASH.prototype.ghash = function (block) {
    var i = -1;
    while (++i < block.length) {
        this.state[i] ^= block[i];
    }
    this._multiply();
};
GHASH.prototype._multiply = function () {
    var Vi = toArray(this.h);
    var Zi = [0, 0, 0, 0];
    var j, xi, lsbVi;
    var i = -1;
    while (++i < 128) {
        xi = (this.state[~~(i / 8)] & (1 << (7 - (i % 8)))) !== 0;
        if (xi) {
            // Z_i+1 = Z_i ^ V_i
            Zi[0] ^= Vi[0];
            Zi[1] ^= Vi[1];
            Zi[2] ^= Vi[2];
            Zi[3] ^= Vi[3];
        }
        // Store the value of LSB(V_i)
        lsbVi = (Vi[3] & 1) !== 0;
        // V_i+1 = V_i >> 1
        for (j = 3; j > 0; j--) {
            Vi[j] = (Vi[j] >>> 1) | ((Vi[j - 1] & 1) << 31);
        }
        Vi[0] = Vi[0] >>> 1;
        // If LSB(V_i) is 1, V_i+1 = (V_i >> 1) ^ R
        if (lsbVi) {
            Vi[0] = Vi[0] ^ (0xe1 << 24);
        }
    }
    this.state = fromArray(Zi);
};
GHASH.prototype.update = function (buf) {
    this.cache = Buffer.concat([this.cache, buf]);
    var chunk;
    while (this.cache.length >= 16) {
        chunk = this.cache.slice(0, 16);
        this.cache = this.cache.slice(16);
        this.ghash(chunk);
    }
};
GHASH.prototype.final = function (abl, bl) {
    if (this.cache.length) {
        this.ghash(Buffer.concat([this.cache, ZEROES], 16));
    }
    this.ghash(fromArray([0, abl, 0, bl]));
    return this.state;
};
export default GHASH;
